June 2013
Volume 54, Issue 15
Free
ARVO Annual Meeting Abstract  |   June 2013
The Effect of Image Quality on the Reliability of Nerve Fiber Layer Measurements with Fourier-Domain OCT
Author Affiliations & Notes
  • Ou Tan
    Ophthalmology, Oregon Health & Science Univ, Portland, OR
  • Xinbo Zhang
    Ophthalmology, Oregon Health & Science Univ, Portland, OR
  • Nils Loewen
    Opthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA
  • Joel Schuman
    Opthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA
  • David Greenfield
    Ophthalmology, Bascom Palmer Eye Institute, Miami, FL
  • Rohit Varma
    Ophthalmology, University of Southern California and Doheny Eye Institute, Los Angeles, CA
  • David Huang
    Ophthalmology, Oregon Health & Science Univ, Portland, OR
  • Footnotes
    Commercial Relationships Ou Tan, Optovue (F), Optovue (P), Carl Zeiss Meditec (P); Xinbo Zhang, None; Nils Loewen, None; Joel Schuman, Carl Zeiss Meditec, Inc. (P); David Greenfield, National Eye Institute (R), Carl Zeiss Meditec (R), Optovue (R), Heidelberg Engineering (R), Allergan (C), Alcon (C), Merz (C), Quark (C), SOLX (C), Biometric Imaging (C), Senju (C); Rohit Varma, Allergan (C), AqueSys (C), Genentech (C), Merck & Co. Inc (C), Replenish (C), Genentech (F), National Eye Institute (F); David Huang, Optovue (F), Optovue (I), Optovue (P), Optovue (R), Carl Zeiss Meditec (P)
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2013, Vol.54, 4820. doi:
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      Ou Tan, Xinbo Zhang, Nils Loewen, Joel Schuman, David Greenfield, Rohit Varma, David Huang, ; The Effect of Image Quality on the Reliability of Nerve Fiber Layer Measurements with Fourier-Domain OCT. Invest. Ophthalmol. Vis. Sci. 2013;54(15):4820.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract
 
Purpose
 

To determine if image quality affects the reliability of peripalliary retinal nerve fiber layer (NFL) thickness.

 
Methods
 

One hundred and nineteen normal and 136 glaucomatous eyes were scanned with optical nerve head (ONH) scan using RTVue Fourier-domain optical coherence tomography (OCT) system (Optovue, Fremont, CA). Each eye was scanned 3 times every visit. Normal subjects were scanned every 6 month and glaucoma subjects every 6 months. Scans from the earliest available 2 visits in the multicenter Advanced Imaging for Glaucoma study (www.AIGStudy.net) were used. Overall NFL thickness was obtained using RTVue 6.1.0.4 software. Marginal signal strength, defined as signal strength index (SSI) between 35 and 45, was detected using the automated RTVue software. Axial or transverse image cropping artifacts were detected using an automated software developed by coauthor Tan. The scans were classified as “weak-signal” (SSI=35-45), “cropped” (cropping artifact detected), or “clean” (SSI>45 and no image cropping). The reliability of NFL measurement was assessed by inter-subject variance in normal eyes, intra-visit repeatability, and inter-visit reproducibility, all evaluated by pooled standard deviation.

 
Results
 

In the normal group, clean scans had significantly smaller inter-subject variance (p<0.001 and p=0.01, F-test) in overall NFL thickness than cropped and weak-signal scans (Table 1). Cropped and weak-signal scans had poorer reproducibility and repeatability than clean scans (p<0.001 for all comparisons by F-test, Table 2).

 
Conclusions
 

Excluding low quality scans (SSI<45, cropping artifacts) may improve the reliability of glaucoma diagnosis and monitoring by OCT NFL thickness measurements. Automated software to detect image cropping may be useful.

 
 
Table 1: Image Quality Effects on Population Distribution of Overall NFL Thickness
 
Table 1: Image Quality Effects on Population Distribution of Overall NFL Thickness
 
 
Table 2 Image Quality Effects on Repeatability and Reproducibility
 
Table 2 Image Quality Effects on Repeatability and Reproducibility
 
Keywords: 550 imaging/image analysis: clinical • 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • 610 nerve fiber layer  
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